JP3137674B2 - Composite injection molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite molding method of a thermosetting resin and a thermoplastic resin. More specifically,
The present invention relates to a composite injection molding method for easily producing, by injection molding, a molded article having a good appearance in which a thermosetting resin in which a mold-formed surface is accurately transferred onto a surface of a thermoplastic resin is coated.

[0002]

2. Description of the Related Art Conventionally, thermoplastic resins have been widely used in various fields because of their good moldability.
Insufficient heat resistance, chemical resistance, flame resistance, abrasion resistance, etc. hindered the expansion of use. On the other hand, a thermosetting resin has the above-mentioned properties better than a thermoplastic resin, but is poor in moldability and shapeability. Therefore, it is desired to obtain a molded product that takes advantage of each other by integrating these resins.

As a material for a composite molded article of a thermosetting resin and a thermoplastic resin, diallyl phthalate resin (hereinafter referred to as DAP) is used in order to partially improve the surface decoration and scratch resistance of furniture such as thermoplastic resin. , Etc.) are known. There is a method in which this is bonded to the surface of a thermoplastic resin molded product, wood or the like with an adhesive to produce a product. Also, a so-called baking coating method is known in which an uncured thermosetting resin is applied to the surface of a part of a molded article made of a highly heat-resistant thermoplastic resin, for example, a glass fiber reinforced polyamide resin, and then cured by heating.
A method of integrating a thermosetting resin and a thermoplastic resin in a mold for injection molding to combine them is disclosed in Japanese Unexamined Patent Publication No.
A 3-37910 publication is known.

[0004]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 63-3791
No. 0 discloses that an uncured thermosetting resin is applied to a mold-molding surface in a liquid state or applied in a sheet state, and the shape at the time of application or application is maintained even by injection of a thermoplastic resin. If necessary, the thermosetting resin is heated to a semi-cured state.

However, the specific method has been a difficult task. One problem is that if the uncured thermosetting resin is applied in liquid form to the mold-molding surface, the uncured thermosetting resin is easily removed by injection of the thermoplastic resin. Also, even if the thermosetting resin is simply applied to the sheet-like material, or the impregnated material is inserted into the mold, the thermoplastic resin is still uncured when the thermoplastic resin is injected by the injection molding machine. Often, the sheet is impregnated with the uncured thermosetting resin in the uneven portion of the molded product, and the sheet is often wrinkled or torn.

Therefore, in the prior art, a method is used in which a mold in which a liquid uncured thermosetting resin is applied to a mold is preheated, and the thermosetting resin is slightly polymerized. However, in practice, the above-mentioned problem of the flow of the thermosetting resin could not be easily solved. In such an operation, a problem such as a long molding cycle occurs, a liquid application material foams by heating, and the adhesion between the thermosetting resin and the thermoplastic resin increases due to the progress of curing by heating. It has been found that new problems such as lowering will arise.

Accordingly, an object of the present invention is to provide a composite injection molding method for easily obtaining a molded article having a good appearance and a three-dimensional structure in which the surface of a thermoplastic resin is coated with a thermosetting resin. .

[0008]

That is, the present invention relates to a method for forming a molten thermoplastic resin in a mold of an injection molding machine in a state where an uncured thermosetting resin is present at a desired position in the mold. After injection filling, and then curing the thermosetting resin, cooling,
In a composite injection molding method characterized by releasing,
When a prepolymer and a solvent of an uncured thermosetting resin or a mixture of a prepolymer, a monomer and a solvent is spray-coated on a mold-molding surface and fixed, 20 seconds after the mixture is fixed. Spray injection of the mixture having a solid content of 50% by weight or more onto a die-molding surface. The weight percent of the solid content of the mixture was measured 20 seconds after the mixture was fixed on the mold-molding surface at the mold-molding surface temperature at which the mixed solution was applied. It refers to the percentage of the weight of the solid prepolymer in the mixture relative to the weight of the mixture.

Hereinafter, the present invention will be described specifically. In producing the composite molded article of the present invention, first, a prepolymer of an uncured thermosetting resin and a solvent, or a mixture of a prepolymer, a monomer, and a solvent, using a spray gun,
It is applied to the mold imprinting surface and is fixed to the mold imprinting surface. Next, the thermoplastic resin is immediately injected into the mold and injected, and integrated with the uncured thermosetting resin fixed on the mold-molding surface. Thereafter, the mold is heated to cure the thermosetting resin. Thereafter, the desired molded product is obtained by cooling and solidifying the molded product and releasing the mold.

The above-mentioned uncured thermosetting resin prepolymer and solvent or a mixture of the prepolymer, monomer and solvent are mixed with a thermosetting resin having a thermoplasticity at a temperature lower than the crosslinking / curing temperature. A mixture of a polymer and a solvent, or a prepolymer, a monomer and a solvent,
A product obtained by adding a catalyst, a release agent, and if necessary, a compatibilizing agent, a reinforcing agent such as glass fiber, or the like to this can be used. When this mixture was spray-coated on the die-molding surface and fixed, the solid content 20 seconds after the mixture was fixed was 5%.
It is at least 0% by weight, preferably at least 80% by weight. Further, the ratio ρr / ρs of the density ρs of the cured thermosetting resin to the density ρr of the fixed uncured thermosetting resin is 0.
It is 33 or more, preferably 0.45 or more, and more preferably 0.90 or more.

The solvent used in the present invention may be any solvent that dissolves the uncured thermosetting resin, but is preferably a solvent that easily volatilizes during spray coating. Preferably, those having a boiling point not higher than the heat deformation temperature of a general-purpose thermoplastic resin, and more preferably those having a boiling point lower than the mold temperature during injection molding of a general-purpose thermoplastic resin are particularly preferred.

The term "thermosetting resin" as used in the present invention is a generic term for a resin which crosslinks and cures when heated to a sufficiently high temperature. Examples of the thermosetting resin suitable for the present invention include a DAP resin, an unsaturated polyester resin, an epoxy resin, and a thermosetting polyurethane, and those having a solid prepolymer at room temperature are particularly desirable. These resins may contain a reinforcing agent such as a catalyst, a bulking agent, glass fiber, mica, and calcium carbonate, if necessary.

An external release agent may be used to facilitate release from the mold surface after cooling and solidification. However, from the viewpoint of productivity and the like, the release agent is added to the thermosetting resin mixture. It is desirable to add The thermoplastic resin to be combined with the thermosetting resin of the present invention includes olefin resins such as polyethylene and polypropylene, polystyrene, styrene-acrylonitrile copolymer, ABS resin, and styrene resins such as styrene-maleic anhydride copolymer. , Polyvinyl chloride, vinyl chloride resin such as vinyl chloride-vinyl acetate copolymer (EVA), polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate resin, polyamide -Engineering resins such as polyphenylene ether resin, polyoxymethylene resin, polymethyl methacrylate resin, polyetherimide resin, polyphenylene sulfide resin, etc. Cellulose derivative resins and blends thereof, and the like, These are glass fiber and iron powder,
It may contain fillers such as talc and calcium carbonate, and ordinary resin additives such as plasticizers.

FIG. 1 shows an example of an injection mold used in the present invention. Fig. 1 shows an example of a three-plate mold.
A coil 3 in which a copper tube is spirally wound is arranged on the back surface of each plate to heat the cavity plate and the core plate, a high-frequency current is passed through the coil, and a cooling water hole is provided in the cavity plate and the core plate. It is effective in shortening the molding cycle. Further, a portion of the master mold such as the fixed mold plate 5 and the movable mold plate 6 that does not need to be heated and does not need to be subjected to high-frequency induction heating is provided with a seal layer 4 made of a nonmagnetic material such as copper or brass. This is effective in shortening the molding cycle. A high-frequency power supply of about 1 to 1000 KHz is convenient.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 A lens of an automobile fog lamp with an approximately square and dish-shaped section of 8 cm × 10 cm as shown in FIG. 1 was formed. The main components of the mold are as shown in FIG. 1 and described above. DAP resin was used as the thermosetting resin.
The composition of the DAP resin mixture used was 92 parts of DAP prepolymer (2-20 mer), DAP monomer-6.
Part, benzoyl peroxide 2 parts, an internal mold release agent containing a fluorocarbon compound and a synthetic organic acid ester derivative as main components.
3 parts were dissolved in 100 parts of acetone.

When this was applied with a spray gun, it was further diluted three times with acetone and applied directly to the mold surface with a thickness of 50 μm. At this time, the mold temperature was previously adjusted to 60 ° C. to promote the evaporation of acetone as a solvent. The powdery prepolymer mixture applied and fixed on the mold surface had a solid content of 82.6%. The ratio (ρr / ρs) between the density ρr of the mixture of the powdery prepolymer applied to the mold surface and the density ρs of the cured product was 0.95.

Next, the mold is closed and A is used as a thermoplastic resin.
Using S resin (acrylonitrile-styrene copolymer), the resin was injected into a mold at a resin temperature of 240 ° C. Further, a high-frequency current of 7 KH and 20 KW is intermittently applied to the coil 3 at intervals of 15 seconds, and the temperature of the cavity plate and the core plate is set to 150 ° C.
For 2 minutes to cure the DAP resin. After that, cooling water was passed through, and the composite resin was cooled and solidified, and then released from the mold to obtain a target composite molded product.

In this case, it is sufficient to heat only the cavity plate 1 in order to cure the DAP resin, but in order to prevent the warpage of the molded product, the core plate 2 is also heated to substantially the same temperature and the cavity plate 1 is heated. It is effective to simultaneously cool the plate and the core plate. The appearance of this composite molded product is good,
The imprinted surface of the mold is accurately transferred to the same or more than the appearance of the normally molded AS resin.

Further, the adhesion of the DAP resin is determined by cross-cutting.
The result of the cellophane peeling test was 0/100, indicating that the film was not peeled at all and sufficient adhesion was obtained. The surface hardness of the DAP resin layer is 3H in pencil hardness, which is much higher than the surface hardness HB of the AS resin. The advantages of the lens of this embodiment are lighter than the conventional fog lamp lens, superior in impact resistance due to stepping stones, and more than anything, such as freedom of design and productivity improvement by directly applying to the mold, There is something immeasurable.

[0020]

EXAMPLE 2 A lens of an automobile fog lamp as shown in FIG. 1 having an approximately square and dish-shaped section of 8 cm × 10 cm was formed. The main components of the mold are as shown in FIG. 1 and described above. DAP resin was used as the thermosetting resin. The composition of the DAP resin mixture used was 92 parts of DAP prepolymer (2-20 mer), DAP monomer-6.
Parts, 2 parts of benzoyl peroxide and 0.3 part of an internal release agent were dissolved in 100 parts of acetone.

When this was applied with a spray gun, it was further diluted three times with acetone and applied directly to the mold surface with a thickness of 50 μm. At this time, the temperature of the mold was previously adjusted to 40 ° C., and the acetone as a solvent was promptly evaporated. At this time, the solid content of the powdery prepolymer mixture applied and fixed on the mold surface was 62.7%. Next, the mold is closed, and glass fiber is used as a thermoplastic resin for 20 minutes.
% ABS resin was injected into the mold at a resin temperature of 240 ° C. Further, a high frequency current of 7 KH and 20 KW is intermittently applied to the coil 3 at intervals of 15 seconds, and a cavity plate,
The DAP resin is cured by maintaining the temperature of the core plate at 150 ° C. for 2 minutes, and then cooling water is passed. After cooling and solidifying the composite resin, it is released from the mold to obtain the desired composite molded product. Was.

The appearance of the composite molded product is good, and the mold imprinted surface is more accurately transferred than the appearance of the normally molded ABS resin. Also, the result of the cross-cut cellophane peel test of the adhesion of the DAP resin was 0/1.
In the case of No. 00, it did not peel off at all and sufficient adhesion was obtained. Also, DAP
The surface hardness of the resin layer is 2H in pencil hardness, which is much higher than the surface hardness 3B of the ABS resin.

[0023]

According to the composite injection molding method of the present invention,
The combination that could not be compounded in the past due to the relationship between the curing temperature condition of the thermosetting resin and the heat distortion temperature of the thermoplastic resin has become possible to form a compound. In addition, by spray-coating a mold obtained by diluting a prepolymer of a thermosetting resin with an arbitrary solvent into a mold, the degree of freedom of the shape of the molded article is remarkably increased. The problem that the thermosetting resin flows due to the injection and filling of the thermoplastic resin has also been improved, eliminating the need for advanced skill in the injection and filling of the thermoplastic resin, making the appearance simple and extremely productive. It has become possible to produce extremely good composite molded products.

[Brief description of the drawings]

FIG. 1 is an example of a schematic cross-sectional view of a composite injection molding mold used in the present invention.

[Explanation of symbols]

 1: Cavity surface 2: Core surface 3: Coil 4: High frequency seal surface 5: Fixed mold plate 6: Movable mold plate 7: Mounting plate

Claims (1)

(57) [Claims] In a state where an uncured thermosetting resin is present at a desired position in a mold of an injection molding machine, a molten thermoplastic resin is injected and filled into the mold, and then the thermosetting resin is filled. After curing, in the composite injection molding method characterized by cooling and releasing, on the mold imprinting surface, a prepolymer and a solvent of an uncured thermosetting resin, or a prepolymer and a monomer and a solvent. When the mixture is fixed by spray coating, the mixture having a solid content of 50% by weight or more after 20 seconds from the fixation of the mixture is spray-coated on a mold molding surface. Composite injection molding method.